Blitz 250g of the biscuits in a food processor with 125ml of the syrup until it resembles fine crumbs. Line a 20cm springform tin with baking parchment, then firmly push the crumbs into the base, transfer to the fridge and chill for 30 mins.
Beat 100ml of the syrup with the cheese and pumpkin until smooth. Whip 200ml of the cream with 100ml of the syrup to soft peaks. Fold into the cream cheese mixture, then spoon over the base and level the top. Cover and freeze overnight.
Lightly whip the remaining cream with the remaining syrup and dollop over the cheesecake. Crumble over the remaining biscuits and drizzle over some extra syrup. Leave to rest for 5 mins before serving.
Speculoos biscuitsTry using speculoos biscuits in the crust for a spiced flavour.